I'm setting up artwork to be screen printed onto clothing, and I have a question on overprinting.

The art contains an illustration that is made up of many overlapping shapes with various spot-color fills, gradients, and strokes. I want to print this illustration on top of a base of white ink. My dilema is: if I do not set the illustration to overprint, it knocks out the white ink base, and if I do set the illustration to overprint, it changes appearance because all of the overlapping items in the illustration overprint each other as welll as the white ink base.

I would like the items in the illustration to not overprint each other, and still have the entire illustration overprint the base of white ink. Possible?

It's possible when you group all the colored objects, turn on overprinting for the group and make that a knockout group (in Transparency palette). Be sure to turn on Overprint preview in Illy so you can see that everything's OK